Overtravel actuating mechanism for a snap action electrical switch



J1me 1965 J. J..DENNISON 3,187,132

OVERTRAVEL ACTUATING MECHANISM FDR A SNAP ACTION ELECTRI L SWITCH I Filed NOV 1952 INVENTOR John dosep'h- Denn \son illli'i in United rates 3,187,132 GVERTRAVEL AtITUATltlG REEQHANEEM FOR A SlNAP AtITION ELE CTRECAL WETCH John doseph Dennison, Cheshire, Conn, assignor' to Manson Electronics Corporation, New York, N331. Filed Nov. 1 5, 1962, Ser. No. 237,556 3 tllaims. (till. Zed-67) This invention relates to snap switches of the type including a contact-carrying arm comprising leaf spring means and relates more particularly to an overtravel actuating means for such a switch.

In the use of snap switches it has often been found desirable to employ on overtravel actuating mechanism, that is, one in which the operating member has a greater distance of travel than necessary to cifect movement of a contact from a normally open or normally closed position to another position, the movable contact being biased to one position. Switches of this type are well known.

Switches of the last-mentioned type are often miniature switches, and it has often been found that the service life of the contact-carrying arm comprising leaf spring means is relatively short due to fatigue effected in the contactcarrying arm through the overtravel operating mechanism. This is a serious drawback to the use of such switches.

One object of the invention is to provide an improved overtravel operating mechanism for a snap switch.

Another object is to provide such an operating mechanism which lends itself well to snap switches of the miniature type.

A further object is to provide in a snap switch an overtravel operating mechanism which effects through engagement therewith a small amount of movement of the contact-carrying arm to achieve movement of the lastmentioned contact from one position to another, thereby reducing fatigue in the last-mentioned arm and adding to the service life thereof.

Other objects will be apparent from the following detailed description of the form of the invention illustrated in the drawing by way of example.

In the drawing:

FIG. 1 is an elevational view of a switch embodying the invention, the switch being shown with one element of the housing removed, parts of the switch being shown in section;

FIG. 2 is a sectional view on line 2-2 of FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing the parts of the switch in ditferent positions;

FIG. 4 is a fragmentary view similar to FIG. 3 but showing parts of the switch in still other positions;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 1; and

FIG. 6 is a plan view of the contact arm showing the same assembled with a support member.

In the drawing-there is illustrated a switch case preferably formed of molded plastic material and having suitable electrical insulation characteristics. The case comprises a body element 10 and a cover element 11 which may fit together tightly to seal out foreign substances. .In the assembled switch the elements it) and 11 may be suitably secured together as by rivets, not shown. The case ele ments 10 and 11 together form openings for the protrusion from the case of a switch-operating plunger 12, a pair of terminals 13 and an electrically conductive support 14. The terminals 13 are fixed in the case in any well-known manner as in the support 14.

As shown in FIG. 1, the terminals 13 are arranged in vertically spaced relation to one another, the upper one carrying a fixed contact 15 and the lower one carrying in a similar manner a similar contact in. Either of the con- Fetented June 1, 1955 tacts 15 or 16 is engageable by a double-faced contact 17 biased towardcontact 15 by contact arm 13.

The contact arm comprises a leaf spring which is supported in the case from the support 14, the support 14 having the configuration best shown in FIGS. 1 and 6. As shown in these views, the support 14 has an upwardly struck abutment 19 notched as at 20. The leaf spring which in the illustrated form constitutes the contact arnr is best shown in FIG. 6.

As shown in the last-mentioned view, the spring is generally oblong having two laterally spaced tension members 21 extending longitudinally of the contact arm and having their ends interconnected. Intermediate the tension members 21 and extending longitudinally of the contact arm in spaced relation from the tension members there is a tongue 22 having a free end and having the other end thereof formed integrally with the aforementioned means interconnecting one pair of ends of the tension members as shown in FIG. 6.

As best shown in the last-mentioned view, the end of the arm 18 from which the aforementioned tongue 22 extends carries the double-faced contact 17, one face of the contact being above the arm and the other below. The other end of the arm is provided with a non-round aperture which snugly receives a boss 23 extending upwardly from the support 14 and stacked over the arm 13 to prevent separation of the two elements, the arrangement being such that angular dislocation of the arm relative to the support 14 is also prevented, that is, angular dislocation on a vertical axis as viewed in FIG. 1. When the arm 1% is assembled with the support 1 the aforementioned tongue 22- is bowed downwardly and the free end thereof engaged in the notch 20 of the abutment 19 of the support, the result being that the tongue 22 is.

maintained under compression while the members 13 Y are maintained under tension, the double-faced contact 1'7 being biased toward the contact 15 as shown in FIG. 1. The actuating mechanism of the switch includes a lever 24 arranged longitudinally of the arm in. The lever 24 is pivoted at one end as by a pair of oppositely extending trunnions 25 (FIG. 5) rockable in sockets formed respectively in the case elements 10 and 11, the lever 24 being swingable on a horizontal axis and having intermediate of its ends adownward projection 26 which spans the tension members 21 of the contact arm 18 for engagement therewith beyond the distal end of the tongue 22 as indicated in FIGS. 1 and 2. The distal end portion'of the lever 24 is provided with a vertically arranged bore enlarged by an upwardly facing counterbore, 27.

A plunger 28 is slidable in the bore in a vertical direction and may take the form of an eyelet, the ends of which are provided with the usual radially extending flanges 29. A coil spring 36 bottoming in the counterbore 27 is compressed between the latter and the upper radial flange 29 of the plunger, the arrangement being such that the plunger 28 is urged upwardly as shown in FIG. 1.

The aforementioned operating plunger 12 cooperates with the spring-biased plunger 28 to effect switch-operating movement of the contact-carrying arm 18 through the lever 24, the arrangement being such that the lever 2 elfects a mechanical advantage in the operation of the switch.

The operating plunger 12 has a button portion 31 protruding above the top of the case. Below this button and fixed thereto is a portion 32 of the plunger lying within the case. The portion 32 extends transversely of the case as shown in FIG. 2 and has oppositely directed flat faces slidably engaged with complemental faces of the respective case elements ltl and 11 to prevent rotation of the. plunger l2.

As best shown in the last-mentioned view the portion Downward movement of the end of the lever 24 carrying the plunger '28 is limited by an abutment 36 formed on the 'case interiorly thereof and engageable by the lastment-ioned end of the lever. a V

-The normal positions of the parts of the switch are shown in FIG. 1. FIG. 3 indicates the point to which the'operating plunger must travel to actuate the contactcarrying arm 18 to achieve movement of the contact 17 from the contact 15 to the contact 1 6. FIG. 4 indicates 'theextent of o-vertravel of the operating plunger after the contact 17 has engaged the contact 16. -As previously indicated, the construction and arrangement of the contact-carrying arm 13 comprising leafspring means is such that the contact 17 normally engages tion 32 of the plunger with the under side of the top of thecaseas shown in FIG. 2; and the plunger 12 is urged to this position :by the spring-pressedplunger 28 carried by'the lever. 24. .The coil spring associated with the plunger .28 and :b'ottoming in the counterbore 27 in the lever forms a resilient stop for upward swinging movement-of that portion of thelever which carries the plung er28 associated with the plunger 12.

. v The operationofth'e snap switch will be manifest from the foregoing description. When the contact-carrying arm 1-8 and the operating plunger 12 are in the positions shown in "FIG. '1, the last-mentioned plunger may be depressed manually or by other means to eliect swinging movement of the lever 24 in a counterclockwisedirection as viewed in FIG. 1 through the spring 30 which resists depression of the plunger 12. Moving against the force of spring .30' continued depression of the plunger 12 effects continued movement of the lever 24 coacting with thecontact-carryingarm 18 through the projection 26 of the-lever to the point where the contact arm achieves a point of maximum stress, at which time the contact 17 snaps :outof engagement with the contact 15 and into en- 'gagementfwith the'contact 16 in a very fast manner in accordance with well-known spring principles.

During :this movement of the operatingzplunger 1-2 from the .pos itionof FIG. 1, the spring-biased plunger 28 rocks with reference tothe plunger 12ias shown in FIG. 3, and i swinging movement .ofithe lever 24 in a counterclockwise direction is limited by engagement of the =lever with the abutment 3 6. Hence no further force may be exerted on the contact car-rying arm "18 through the lever 24. However, the operating plunger may have an overtravel through its cooperation with the spring-biased plunger 28.

The transl housing, said arm being effective to-returnsaidfirst plung-1 t From the foregoing, it will be evident that in accordance with the description there is provided an improved snap-action switch which is ofsimpleyet reliable construction and which is adapted for mass production as by automated techniques. lit will be apparent too that the switch has an improved overtravel operating mechanism which in eifect extends the service life of the leaf spring carrying the movable contact by reducing fatigue therein. A mechanical advantage is achieved by the employment of the lever engageable with the contact-carrying spring. Yet the spring in the region where it is contacted by the lever has only a small travel in the operation of the switch, but at the same time the operating member is permitted a relativelylong distance to travel. The construction is well adapted to switches of the miniature type.

While only one formof the overtravel actuating mechanism for a snap switch has been shown in the drawing and described above, it will be apparent to those versed in the art that the mechanism may take other {forms and is susceptible of various changes in details without departing from the principles of theinvention and the scope of the appended claims.

What I claim is: a H

1. In an overtravel actuating mechanism for a snap switch having a housing and a resilient contact arm mounted on the housing and having a stable position and having an unstable position in which it contacts a contact mounted on the housing, the improvement which comprises an arm-actuating lever pivoted on the housing engaging said arm and being swingable toward one extreme position to move the armito said unstable position thereof and being swingable in the opposite direction toward a second extreme position, plunger means for actuating said lever, including a first plunger slidably mounted in the -hou'sing,'a second plunger, said second plunger being engageable with the first plunger and slidable in said lever, and 'a spring coac ting between said lever and said second plunger urging the latter. toward the first plunger, said first plunger having a normal position and being. movable from the latter to a position in which the lever assumes the first-mentioned extreme position and the contact arm assumes said unstable position in which it contacts said contact on the er to the normal position thereof through movement of the lever to said'second extreme position thereof.

2. An overtravel actuating mechanism for a snap switch as defined in claim 1 wherein means is provided on said lever coacting with means on said housing for limiting movement of the former in a direction toward said arm. s

3. An overtravel actuating mechanismfor a snapswitch as defined-in .claim .l-wherein means is provided on the first plungercoacting with means on the housing to limit movement ofthe former from its normal position toward said lever, and means is provided on said lever coaoting with means on said housing for limiting movementof the former in a direction toward said arm.

Continued'depression' oftthe .plunger 12 etfects down ward sliding movement of the plunger 28 in the bore of the lever ,24 further compressing the spring 30. When 'ReferencesCitedbythe Examiner J UNITED STATESPATENTS 2,354,027. 7/44 Kaminky a. zoo-s7 3,033,953 5/62 Schwerjke 200-,--67 3,075,079 7 1/63 Millerwise 200-468 BERNARD A. GILHEANY, Primary Examiner. ROB RTIK. SCHAEEER, Examiner. a

switch-operating 

1. IN AN OVERTRAVEL ACTUATING MECHANISM FOR A SNAP SWITCH HAVING A HOUSING AND A RESILIENT CONTACT ARM MOUNTED ON THE HOUSING AND HAVING A STABLE POSITION AND HAVING AN UNSTABLE POSITION IN WHICH IT CONTACTS A CONTACT MOUNTED ON THE HOUSING, THE IMPROVEMENT WHICH COMPRISES A ARM-ACTUATING LEVER PIVOTED ON THE HOUSING ENGAGING SAID ARM AND BEING SWINGABLE TOWARD ONE EXTREME POSITION TO MOVE THE ARM TO SAID UNSTABLE POSITION THEREOF ABD BEING SWINGABLE IN THE OPPOSITE DIRECTION TOWARD A SECOND EXTREME POSITION, SWITCH-OPERATING PLUNGER MEANS FOR ACTUATING SAID LEVER, INCLUDING A FIRST PLUNGER SLIDABLY MOUNTED IN THE HOUSING, A SECOND PLUNGER, SAID SECOND PLUNGER BEING ENGAGEABLE WITH THE FIRST PLUNGER AND SLIDABLE IN SAID LEVER, AND A SPRING COACTING BETWEEN SAID LEVER AND SAID SECOND PLUNGER URGING THE LATTER TOWARD THE FIRST PLUNGER, SAID FIRST PLUNGER HAVING A NORMAL POSITION AND BEING MOVABLE FROM THE LATTER TO A POSITION IN WHICH THE LEVER ASSUMES THE FIRST-MENTIONED EXTREME POSITION AND THE CONTACT ARM ASSUMES SAID UNSTABLE POSITION IN WHICH IT CONTACTS SAID CONTACT ON THE HOUSING, SAID ARM BEING EFFECTIVE TO RETURN SAID FIRST PLUNGER TO THE NORMAL POSITION THEREOF THROUGH MOVEMENT OF THE LEVER TO SAID SECOND EXTREME POSITION THEREOF. 